docs: def wrap(self, data):
          """Wrap this with the root schema definitions."""
          if self.nested:  # no need to wrap, will be in outer defs
              return data
  
          name = self.obj.__class__.__name__
          self._nested_schema_classes[name] = data
          root = {
              'definitions': self._nested_schema_classes,
              '$ref': '#/definitions/{name}'.format(name=name)
          }
          return root